While recording an image of a sample to be analyzed using a particle beam microscope, a primary particle beam generated by the particle beam microscope is directed onto predetermined locations of the sample to be analyzed and secondary particles, such as secondary electrons, dislodged from the sample due to interaction of the primary particle beam with the sample are detected in order to obtain information about the location of the sample onto which the particle beam is directed. The intensities of secondary particles detected at a plurality of locations on the sample onto which the particle beam is directed represent an image of the sample to be analyzed. For this, the primary particle beam hitting the sample and the secondary particles dislodged from the sample alter the state of charge of the sample, in particular on its surface, so that a positive or negative charge of the sample may be generated. This charge of the sample alters, on the one hand, the impinging energy of the primary particle beam and the rate at which the secondary particles may reach a detector for their detection. Therefore, the intensity of detected secondary particles does not merely change in dependence of the location onto which the primary particle beam is directed onto the sample but also in dependence of the time during which the analysis is performed.
For this reason, particle beam microscopes conventionally include apparatuses in order to reduce a charge of the sample generated during the analysis. Such an apparatus is, for example, an electron beam source which directs an electron beam different from the primary particle beam onto the sample wherein the electron beam has an adjustable kinetic energy. In dependence of this kinetic energy positive or negative electric charge can be deposited onto the sample as the electrons hitting the sample there generate secondary electrons emanating from the sample; and the rate of generation of the secondary electrons is energy-dependent.
It has been found that the conventional method of reducing a charge of the sample using electron beams often does not provide a satisfactory reduction of the charge of the sample.